In human anatomy, men have longer urethras than women. This means that women have bladder infections more often, because their bladders are closer to the outside. Because the male urethra is longer and is not straight, inserting a catheter (tube to help urination) is more difficult in men.

In women, the urethra is 2.5-4 cm (1-1.5 in) long. Its opening to the outside of the body is part of the vulva (the area between a woman's legs). The female urethra is between the clitoris and the opening to the vagina. In men, the urethra is about 20 cm (8 in) long and its opening to the outside of the body is at the end of the penis.